MAL-2026-17478

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-field-sizing-polyfill/MAL-2026-17478.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-17478
Published
2026-10-04T23:14:01Z
Modified
2026-10-04T23:30:06Z
Summary
Malicious code in css-field-sizing-polyfill (npm)
Details

-= Per source details. Do not edit below this line.=-

Source: amazon-inspector (549bb8820cb6a8a35853826d17b64df14c0561b83790192a33c5dc76dbad53b9)

The package advertises itself as a CSS field-sizing polyfill but ships thunderboltRegistry.js, which runs an IIFE at module load time. The IIFE shells out via child_process.execSync to run id, whoami, uname -a, ifconfig/ip addr, and cat /etc/hosts, then transmits the collected output together with hostname, Node version, platform, and pid as query-string parameters to the hardcoded plaintext endpoint http://dxpoc.gt.tc/callback.php/bb8968d0f67000433bf7005dd5ad2d1f. The module also exports proxied stubs for Wix-internal names (thunderboltRegistry, siteAssetsRegistry, documentManagementRegistry, editorRegistry, corvidRegistry) and ships a registry-manifest.min.json pointing at static.parastorage.com, indicating a dependency-confusion impersonation of Wix internal packages so that an internal resolver pulling this public name will trigger the beacon. The reconnaissance behavior is unrelated to the declared CSS polyfill purpose and fires on any require() of the package.

Database specific 
{
    "malicious-packages-origins":  [
        {
            "id":  "IN-MAL-2026-020885",
            "import_time":  "2026-10-04T23:16:30.37814939Z",
            "modified_time":  "2026-10-04T23:14:01Z",
            "sha256":  "549bb8820cb6a8a35853826d17b64df14c0561b83790192a33c5dc76dbad53b9",
            "source":  "amazon-inspector",
            "versions":  [
                "1.0.0"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / css-field-sizing-polyfill

Package

Name
css-field-sizing-polyfill
View open source insights on deps.dev
Purl
pkg:npm/css-field-sizing-polyfill

Affected ranges

Affected versions

1.*
1.0.0

Database specific

cwes 
[
    {
        "cweId":  "CWE-506",
        "description":  "The product contains code that appears to be malicious in nature.",
        "name":  "Embedded Malicious Code"
    }
]
indicators 
{
    "evidence_files":  [
        {
            "path":  "thunderboltRegistry.js",
            "sha256":  "a485cb48081ea590cab385a405886cfe6f30af7d415f30bc8d7937ace461b928",
            "tlsh":  "e87154a5b99df02065c33438cb7f4049b4bbc6672d6caee0744899b01f7985c01be6f8"
        }
    ],
    "package_integrity":  [
        {
            "filename":  "css-field-sizing-polyfill-1.0.0.tgz",
            "hashes":  {
                "sha1":  "e09bee57d7fff944baacc31a3433e4dcb8121aa3",
                "sha512_sri":  "sha512-+h+9uvwaIvYna5LXfs1X6VR5dkAQnXxLW7/SUVVncEloyTE1KaaWjHag57x3NPkbvF1ReijGWLc+o0Y2o1q0oA=="
            }
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/css-field-sizing-polyfill/MAL-2026-17478.json"